1. Field of the Invention
The present invention relates to a judgment which is made as to an input signal in an image processing apparatus.
2. Related Background Art
The art of automatically judging whether an original is a monochrome original or a color original by judging an signal inputted to a color image processing apparatus, and executing a monochrome copy operation in the case of a monochrome original and a color copy operation in the case of a color original, is proposed in U.S. Pat. No. 4,953,012 by the same assignee as the present applicant.
The art of producing a clear copy without any color deviation of a black character portion contained in a color original by detecting the black character portion in the color original to print it in black only and by printing the remaining portions in color, is proposed by the same assignee as the present applicant in U.S. patent application Ser. No. 519,447, Ser. No. 519,448 and Ser. No. 519,500, now U.S. Pat. Nos. 5,119,185, 5,239,383 and 5,113,252, respectively.
However, an apparatus does not exist which has the sophisticated image processing capability to judge the kind of original--whether a monochrome original or a color original--and select a corresponding copy mode on the basis of the above-described art, and to extract a black character portion from the original and produce a printout without any color deviation.
If there are separately provided a judgment circuit for making the above-described automatic color judgment in which the kind of original--whether a monochrome original or a color original--is automatically judged and a judgment circuit for judging whether each pixel has black for the purpose of producing a black printout, the construction of the apparatus becomes complicated.
A judgment result may differ for an identical original due to the non-uniformity of the characteristics of individual reading optical systems.
In addition, even if an identical original is to be processed, individual operators make different judgments as to whether the original is a chromatic color original or an achromatic color original, according to their purposes of use, desires or the like.